Re: [RFC PATCH 4/7] memcg: sleep during flushing stats in safe contexts

[Johannes Weiner]

On Thu, Mar 23, 2023 at 04:00:34AM +0000, Yosry Ahmed wrote:
> @@ -644,26 +644,26 @@ static void __mem_cgroup_flush_stats(void)
>  		return;
>  
>  	flush_next_time = jiffies_64 + 2*FLUSH_TIME;
> -	cgroup_rstat_flush(root_mem_cgroup->css.cgroup, false);
> +	cgroup_rstat_flush(root_mem_cgroup->css.cgroup, may_sleep);

How is it safe to call this with may_sleep=true when it's holding the
stats_flush_lock?

>  	atomic_set(&stats_flush_threshold, 0);
>  	spin_unlock(&stats_flush_lock);
>  }